Forty years later, it was discovered that the skull pieces had been fraudulently modified to appear ancient, and planted in the sites.

New collaborative research, published in the journal Royal Society Open Science, used high-precision measurements, chemical analysis and 3D imaging to demonstrate the forger was almost certainly Dawson.

The findings come 100 years after Dawson’s death.

The jawbone from the Piltdown I site, alongside a molar discovered at Piltdown II

A sharpened piece of elephant thighbone, known as the Piltdown cricket bat

'Our team has identified consistent working methods that suggest a single perpetrator was at work.'

An unbelievable find

In 1912, Dawson wrote to Woodward, the Keeper of Geology at the Natural History Museum, claiming he had found pieces of human skull in gravel beds at Piltdown, Sussex.

More specimens were unearthed during excavations in the gravel, which dates back to the Pleistocene Epoch. This site became known as Piltdown I.

The finds included five human skull fragments, an ape-like jawbone with two teeth and a variety of animal fossils and primitive stone tools.

All of them were stained with the same dark red-brown colour as the ancient gravel.

Excavations underway at Piltdown in about 1913. Charles Dawson is sitting on the left, and Arthur Smith Woodward stands on the far right.

The jawbone did not look human but the teeth it held did, appearing to have been worn down in a typically human way.

Woodward and Dawson claimed all this evidence pointed to a human ancestor living at least 500,000 years ago.

Excavations continued in 1913 and 1914, with more important finds including a canine tooth and a carved slab of bone shaped like a cricket bat.

Dawson also discovered a second site, known as Piltdown II, where he unearthed a second collection of skull fragments and a molar tooth.

The forgeries helped to misdirect the study of anthropology for decades.

Uncovering the fraud

After Dawson died in 1916, no other specimens were found.

Some anatomists doubted from the beginning the idea that all the remains belonged to a single individual.

In the early 1950s, a team devised a series of objective tests to try to uncover the truth. While these tests would be considered basic by today's standards, they demonstrated the bones had been faked.

Through fluorine testing, Dr Kenneth Oakley, a geologist at the Museum, discovered that the Piltdown remains were only 50,000 years old at most - not nearly old enough to be the missing link Dawson had claimed they were.

In 1955 it was revealed that most of the material had been artificially stained brown to match the local gravels.

New discoveries

New technologies have allowed scientists to subject the bones to fresh scrutiny.

The research team found that it is highly likely a single orangutan specimen and at least two human specimens, possibly from the medieval period, were used to create the fake fossils.

We now know the orangutan specimen was likely a member of the subspecies that lives in Sarawak, Borneo.

CT scans revealed the teeth were filled with gravel from the Piltdown sites. This image shows pebbles in the molar found at Piltdown II.

The research reveals that the whole collection of bones was prepared for the fraud in the same way.

Prof Stringer explains, 'The same modifications were made on the orangutan and human material from both the Piltdown sites.

Through our scientific tests, we have shown it is likely that the same orangutan jaw was used.

'It points to the central involvement of Charles Dawson, the only person known to be connected with the supposed discoveries at the second Piltdown site.'

X-ray imaging and high-resolution CT scans showed several of the bones and teeth had been loaded with gravel and the holes plugged with small pebbles, all of which came from sediment similar to that found at Piltdown.

As well as this, the same putty was used throughout the bones to both hold the gravel plugs in place and restore one of the teeth in the orangutan jaw.

DNA analysis has linked the canine and molar teeth from the two separate Piltdown sites to the same orangutan individual.

Lead author Dr Isabelle De Groote from Liverpool John Moores University, adds, ‘Although multiple individuals have been accused of producing the fake fossils, our analyses to understand the modus operandi show consistency between all the different specimens and on both sites.

'It is clear from our analysis that this work was likely all carried out by one forger: Charles Dawson.’

Charles Dawson

Dawson would have known what the scientific community was expecting from a missing link between apes and humans.

However, the analysis revealed the forger was not a trained conservator. Some of the work shows inexpert skills - which resulted in fractured bones, the putty setting too fast and teeth cracking while being filed down.

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